TITLE: GCN CIRCULAR NUMBER: 32599 SUBJECT: IceCube-220928A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 22/09/28 13:32:31 GMT FROM: Dr. Massimiliano Lincetto at Ruhr-Universitaet Bochum lincetto@astro.rub.de

The IceCube Collaboration (http://icecube.wisc.edu/) reports:

On 22-09-28 at 12:32:38.30 UT IceCube detected a track-like event with a moderate probability of being of astrophysical origin.  The event was selected by the ICECUBE_Astrotrack_Bronze alert stream. The average astrophysical neutrino purity for Bronze alerts is 30%. This alert has an estimated false alarm rate of 1.99 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection.

After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon_g_b/137096_70551815.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 22-09-28

Time: 12:32:38.30

RA: 207.42 (+1.41 / -2.52 deg  90% PSF containment) J2000

Dec: +10.43 (+0.98 / -0.98 deg 90% PSF containment) J2000

We encourage follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino.

Two gamma-ray sources listed in the 4FGL-DR2 Fermi-LAT catalog are located within the 90% containment of the best-fit candidate neutrino position. The sources are 4FGL J1351.3+1115 and 4FGL J1342.6+0944, located 0.92 and 1.86 deg away from the best-fit position, respectively.

The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc@icecube.wisc.edu